1. Field of the Invention
The present invention relates to a press-connecting terminal with press-connecting blades formed so that an electric wire end is press-fitted therebetween and also to a method for manufacturing the same.
2. Description of the Related Art
FIG. 11(a) shows a conventional press-connecting terminal 1. A contact portion 2 which is brought into contact with a mating terminal is formed on one side of this press-connecting terminal 1, and an electric wire joint 3 is formed on the other side thereof. A pair of electric wire holding leaves 4, 4 are formed on the rear end side of the electric wire joint 3, and a press-connecting portion 5 is provided between the electric wire holding leaves 4, 4 and the contact portion 2. The press-connecting portion 5 is arranged so that two pairs of opposed press-connecting blades 8a, 8b are formed for a pair of side walls 7a, 7b which are formed by bending in the same direction from both sides of a bottom wall 6, each of the press-connecting blades 8a, 8b being cut-bent in such a way as to extend in a direction perpendicular to each of the side walls 7a, 7b above the bottom wall 6.
This press-connecting terminal 1 is prepared through the steps of punching the contact portion 2 and the electric wire joint 3 in a development state from a previously plated material and bending them into predetermined shapes. When the electric wire joint 3 is punched into the development state, the aforesaid press-connecting blades 8a, 8b in the development state are also cut off the respective side walls 7a, 7b in the development state.
The end of a covered electric wire is press-fitted into the gap between the pairs of press-connecting blades 8a, 8b to rupture the covered portion of the covered electric wire by means of the press-connecting blades 8a, 8b. When the conductor portion of the covered electric wire is brought into contact with the press-connecting blades 8a, 8b, the end of the covered electric wire and the press-connecting terminal 1 are electrically connected to each other.
As shown in FIG. 11(b), however, an edge face 9 of the press-connecting blade 8b has a ruptured face as it has been cut off the side wall 7b and has not been plated. For this reason, the edge face 9 of the press-connecting blade 8b is not smooth and has been brought into contact with the conductor with lower reliability.
Thereupon, the edge faces of the press-connecting blades 8a, 8b need plating after the press-connecting terminal 1 is formed. However, there exits a problem arising from an increase in costs in a case where a so-called post plating process is performed in that the edge faces have to be plated after the press-connecting terminal 1 is formed in comparison with a case where the plate material is plated before the press-connecting blades 8a, 8b are bent from the respective side walls 7a, 7b, that is, before they are punched into the development state because the press-connecting terminal is complicated in shape.
On the other hand, press-connecting terminals each having press-connecting blades whose edge faces are free from rupture are described in Japanese Patent Unexamined Publication Nos. Sho. 50-114592 and Sho. 54-158689. The press-connecting terminal 10 described in Japanese Patent Unexamined Publication No. Sho. 50-114592 is, as shown in FIGS. 12(a), 12(b), and 12(c), formed with a pair of opposed press-connecting blades 13a, 13b which are formed by punching a pair of side walls 12a, 12b of a press-connecting portion 11 inward, respectively. With the blades 13a, 13b, their contact portions with a conductor have been plated, whereby the reliability of the electrical connections with respect to the conductor can be secured satisfactorily.
The press-connecting terminal 15 described in Japanese Patent Unexamined Publication No. Sho. 54-158689 is, as shown in FIGS. 13(a), 13(b), and 13(c), formed with a pair of opposed press-connecting blades 18a, 18b which are formed by punching a pair of side walls 17a, 17b of a press-connecting portion 16 inward, respectively. In this press-connecting terminal 15 like the press-connecting terminal 10, the contact portions of the press-connecting blades 18a, 18b with respect to a conductor have also been plated, whereby the reliability of the electrical connections with respect to the conductor can be secured satisfactorily.
In the press-connecting terminals 10, 15 having the press-connecting blades 13a, 13b, 18a, 18b as described in Japanese Patent Unexamined Publication Nos. Sho. 50-114592 and Sho. 54-158689, since the edge faces of the respective press-connecting blades 13a, 13b, 18a, 18b are arcuate in shape, the covered portion of the covered electric wire is difficult to cut off and consequently satisfactory electric connection with the conductor portion may hardly be obtainable. In the press-connecting terminals 10, 15 described in the above patent publications, the force of holding the covered electric wire is weak as the covered-wire catching portions of the press-connecting blades 13a, 13b, 18a, 18b are small and when external force is applied in the axial direction of the electric wire while the wire harness is being pulled, inconvenience tends to occur in that an electric wire 14 easily slips off the press-connecting terminal 10.
Therefore, it is considered to narrow the width L of the leading end portion of the press-connecting blade 18b in such a manner as to overlap the punched portions out of the side wall 17b as shown in FIG. 13(c). In this case, however, the width L of the leading end portion of the press-connecting blade 18b cannot be decreased to less than twice as thick as the plate of the side wall 17b, and this results in failure to ensure that the covered portion of the covered electric wire is cut off.